Ictal and interictal SPECT findings in childhood absence epilepsy

Yenı, Seher Naz; Kabasakal, Levent; Yalçınkaya, Cengiz; Nişli, Cavit; Dervent, Ayşın

doi:10.1053/seiz.2000.0400

Cited by 32 publications

(22 citation statements)

References 13 publications

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“…32 Recent EEG-fMRI studies of CAE and related forms of generalized epilepsy demonstrate significant BOLD signal changes during seizures in a complex network of cortical and subcortical areas. 8,10,11,13,16 Interestingly, CAE characteristically displays widespread, bilaterally synchronous SWD on EEG recordings [5][6][7]33 and bilaterally symmetric BOLD fMRI changes during seizures. [8][9][10]16 The present findings support the notion that abnormal bilateral network synchrony occurs during the interictal period as well, operating at a slower time scale, and preferentially involving the lateral orbitofrontal cortices.…”

Section: Discussionmentioning

confidence: 99%

Resting functional connectivity between the hemispheres in childhood absence epilepsy

Xiang¹,

Guo

Killory

et al. 2011

Neurology

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Objective:The fundamental mechanisms by which childhood absence epilepsy (CAE) changes neural networks even between seizures remain poorly understood. During seizures, cortical and subcortical networks exhibit bihemspheric synchronous activity based on prior EEG-fMRI studies. Our aim was to investigate whether this abnormal bisynchrony may extend to the interictal period, using a blood oxygen level-dependent (BOLD) resting functional connectivity approach.Methods: EEG-fMRI data were recorded from 16 patients with CAE and 16 age-and gendermatched controls. Three analyses were performed. 1) Using 16 pairs of seizure-related regions of interest (ROI), we compared the between-hemisphere interictal resting functional connectivity of patients and controls. 2) For regions showing significantly increased interhemispheric connectivity in CAE, we then calculated connectivity to the entire brain. 3) A paired-voxel approach was performed to calculate resting functional connectivity between hemispheres without the constraint of predefined ROIs. Results:We found significantly increased resting functional connectivity between hemispheres in the lateral orbitofrontal cortex of patients with CAE compared to normal controls. Enhanced between-hemisphere connectivity localized to the lateral orbitofrontal cortex was confirmed by all 3 analysis methods.Conclusions: Our results demonstrate abnormal increased connectivity between the hemispheres in patients with CAE in seizure-related regions, even when seizures were not occurring. These findings suggest that the lateral orbitofrontal cortex may play an important role in CAE pathophysiology, warranting further investigation. In addition, resting functional connectivity analysis may provide a promising biomarker to improve our understanding of altered brain function in CAE during the interictal period. Neurology Childhood absence epilepsy (CAE) is increasingly recognized as a disorder characterized by impaired function both during seizures, and in the interictal period.1-4 Notably, 3-4 Hz spikewave discharges (SWD) seen in CAE 5-7 and their associated blood oxygenation level-dependent (BOLD) fMRI changes [8][9][10][11][12][13][14][15][16] are bilateral and fairly symmetric. Evidence from animal models indicates that this bihemispheric synchrony during SWD is mediated by the corpus callosum. 17,18 We hypothesize that abnormal bihemispheric synchrony persists in the interictal period, and may participate in generating abnormal function, including enhanced bilateral excitability. The possible role of abnormal long-range bilateral synchrony during the interictal period in CAE has not been previously investigated.The recent development of the resting functional connectivity approach to fMRI has provided a window to observe intrinsic brain activity in health and disease. This method has been used to

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Section: Discussionmentioning

confidence: 99%

Resting functional connectivity between the hemispheres in childhood absence epilepsy

Xiang¹,

Guo

Killory

et al. 2011

Neurology

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“…A fMRI study also showed significant hemodynamic changes in the bilateral thalamic and cortical areas during the generalized spike and wave or polyspike and wave bursts in IGE patients [1]. Furthermore, a 99m Tc-HMPAO SPECT study of 6 patients with childhood absence epilepsy reported a diffuse increase in cerebral blood flow including thalamus during hyperventilation [40] and an H 2 15 O PET study showed a mean global increase in blood flow during typical absence and a focal increase of thalamic blood flow following hyperventilation-induced absences with generalized spike-wave discharges [30]. These findings suggest the key role of the thalamo-cortical networks in the pathogenesis of all subsyndromes of IGE.…”

Section: Introductionmentioning

confidence: 95%

Cerebral blood flow abnormality in patients with idiopathic generalized epilepsy

2008

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“…Human and animal studies have shown large increases in neuronal activity, CBF, and metabolism during GTCS (reviewed in . However, some investigators have shown increases in CBF during SWD (Prevett et al, 1995;Yeni et al, 2000), whereas others have shown the opposite (Bode, 1992;Nehlig et al, 1996;Sanada et al, 1988;Sperling and Skolnick, 1995).…”

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confidence: 97%

Relative Changes in Cerebral Blood Flow and Neuronal Activity in Local Microdomains during Generalized Seizures

Nersesyan

Hermán

Erdogan³

et al. 2004

J Cereb Blood Flow Metab

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Summary:There is broad agreement that generalized tonicclonic seizures (GTCS) and normal somatosensory stimulation are associated with increases in regional CBF. However, the data regarding CBF changes during absence seizures are controversial. Electrophysiologic studies in WAG/Rij rats, an established animal model of absence seizures, have shown spikewave discharges (SWD) that are largest in the perioral somatosensory cortex while sparing the visual cortex. Recent functional magnetic resonance imaging (fMRI) studies in the same model have also shown localized increases in fMRI signals in the perioral somatosensory cortex during SWD. Because fMRI signals are only indirectly related to neuronal activity, the authors directly measured CBF and neuronal activity from specific microdomains of the WAG/Rij cortex using a specially designed probe combining laser-Doppler flowmetry and extracellular microelectrode recordings under fentanyl/haloperidol anesthesia. Using this approach, parallel increases in neuronal activity and CBF were observed during SWD in the whisker somatosensory (barrel) cortex, whereas the visual cortex showed no significant changes. For comparison, these measurements were repeated during somatosensory (whisker) stimulation, and bicuculline-induced GTCS in the same animals. Interestingly, whisker stimulation increased neuronal activity and CBF in the barrel cortex more than during SWD. During GTCS, much larger increases that included both the somatosensory and visual cortex were observed. Thus, SWD in this model produce parallel localized increases in neuronal activity and CBF with similar distribution to somatosensory stimulation, whereas GTCS produce larger and more widespread changes. The normal response to somatosensory stimulation appears to be poised between two abnormal responses produced by two physiologically different types of seizures.

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Ictal and interictal SPECT findings in childhood absence epilepsy

Cited by 32 publications

References 13 publications

Resting functional connectivity between the hemispheres in childhood absence epilepsy

Resting functional connectivity between the hemispheres in childhood absence epilepsy

Cerebral blood flow abnormality in patients with idiopathic generalized epilepsy

Relative Changes in Cerebral Blood Flow and Neuronal Activity in Local Microdomains during Generalized Seizures

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